Tidal power is renewable because _________

Tidal energy is a renewable energy source that uses the natural rise and fall of ocean tides and currents. It's caused by the gravitational interaction between the Earth, the sun, and the moon.  Tidal energy is harnessed by converting the energy from tides into useful forms of power, mainly electricity. Tidal energy is captured using either a turbine or a barrage. When the tide comes in, water is impounded in one or more reservoirs. At low tide, the water in these reservoirs is released to drive hydraulic turbines and their coupled electric generators.  Tidal energy is efficient at low... Show more

Tidal energy is a renewable energy source that uses the natural rise and fall of ocean tides and currents. It's caused by the gravitational interaction between the Earth, the sun, and the moon. 

Tidal energy is harnessed by converting the energy from tides into useful forms of power, mainly electricity.
Tidal energy is captured using either a turbine or a barrage. When the tide comes in, water is impounded in one or more reservoirs. At low tide, the water in these reservoirs is released to drive hydraulic turbines and their coupled electric generators. 
Tidal energy is efficient at low speeds and can generate electricity at very low speeds. Tides are more predictable than the wind and the sun. 

Note: Tidal energy is intermittent, from diurnal (once per day) and semidiurnal (twice daily), to fortnightly (spring-neap) timescales.

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